Convert Other Server Power Supply for RC Use

The following article is nothing more than a project report. I take no responsibility for how others may use this information.

After my success with the HP power supply (PS), I started a search for other models. That lead me to this Dell unit. I grabbed a pair to play with and this is what I have found.
The Dell 700W units (model NPS-700AB)
Doing some research, I found out that these PS units come out of the Dell PowerEdge 2850 series servers. They are larger than the HP DPS-600PB PS and the fan is much louder but they do offer a few benefits over the HP, including 125W more output, better cooling and an output that is slightly adjustable.

Dell NPS-700AB

♣ Notes, Annoyances and Updates
I found out that the only way to fully remove the latch mechanism is to cut off the mount from one side of the case, so I just left it there.
The fan in these units is very aggressive. It does a great job of keeping the unit cool but it is not temperature controlled, so it is very, very loud.
There is no fan shield and this fan is not of the friendly type, so lets just say I am keeping my finger clear of it. I might install a 60mm wire fan shield if it becomes a problem.

The business ends. Wow no fan shield!

I found out that this PS has a fine voltage adjustment pot inside the unit. I measured an initial voltage output of 12.18V, and found that I could adjust it from about 11.3V-12.9V.
In testing, these units have APFC (as I believe most server units do). Under a 10A load my Kill-A-Watt reported the PF as a perfect 1.
In my travels I found out that there are 2 models of this unit, one with a small label like the ones I got and one that has a much larger label. The units appear interchangeable in terms of powering a server but they have much different internals.

The important pins.
Mods complete.
12V output voltage adjustment pot.Turn CCW to increase voltage.

The Dell 550W Units (Model AA23300)
When I was researching other units I came across these 550W models but passed on them. After receiving the 700W models and finding out just how freaking loud they are, I thought I would try a pair of these. These small units are used in PowerEdge 1850 series servers. They have the same hot-swap plug as the NPS-700AB units and so far it seems to be wired the same.

I took the units, modified them to work outside the server and intended to wire them in series. I opened up one and found out how the DC ground was connected to the case. Turns out it is only connected with one screw but I saw no easy way to disconnect it at the board. I used some heat shrink and a paper spacer to isolate it and that did the trick. I then attached them together and wired them in series, and that is what is pictured below.

♣ Notes, annoyances and updates
The latch mechanism is buried in the unit. It looks to be attached like the HP 575W models but I didn’t want to take it that far apart to find out. Instead I just zip-tied the handle down to pull the catches in.
The fan are not too bad. Yes there are 2 stacked. I have not loaded it yet but I think they might be temp controlled. Time will tell.
I did test for APFC and they do have it.

A Nicely Finished Unit

Wrapped in 100mm Turnigy shrink wrap
1/8″ neoprene foam on the bottom
10awg wire series connection and 4mm bullets soldered directly to output spades, both 24V and 12V outputs

All information has been referenced from the Tjinguytech.